GATE 2022 Rapid Revision Quiz 3

Displacement thickness in a flow governed by is 0.25δ. The value of n is __.

In a Francis turbine having a net head of 660 m with purely radial out flow, the whirl velocity was 17 m/s and the runner diameter at inlet is 2.1 m. The turbine runs at 600 rpm. The hydraulic efficiency of the turbine is:

For a flow velocity distribution is given as where u is local velocity and U is free stream velocity. Displacement thickness is given by and momentum thickness is given by θ.

Then, =_________.

A Francis turbine produces 13.7 MW of power, running at 150 rpm under a head of 31 m. The surrounding atmospheric pressure and vapor pressure, where the turbine is installed is 12 m of water and 0.4 m of water respectively. Determine the maximum possible height of the straight draft tube, in order to avoid the onset of cavitation phenomenon?
(Given, For a Francis Turbine, the critical value of Thomas cavitation factor is given by: 

where N_s= Specific Speed(in rpm) )

Consider two hydraulic turbines having identical specific speed and effective head at the inlet. If the speed ratio (N₁/N₂) of the two turbines is 2, then the respective power ratio (P₁/P₂) is ________

A 10 cm diameter jet of water strikes a curved vane with a velocity of 25 m/sec. The inlet angle of the vane is zero and the outlet angle is 30° .when the vane is stationary determine the resultant force on the vane_____ N.
(Take density of water as 998 kg/m³)